The present invention relates to the encoding of a geographic location in an address line associated with a web page. More particularly, the present invention relates to a method of encoding latitude and longitude coordinates in a Uniform Resource Locator (URL) associated with a web page.
Certain web sites, such as those that involve serving up maps of arbitrary locations, require an encoding of latitude/longitude coordinates. There are at least two ways to accomplish the encoding. One is to provide the coordinates in a URL that is utilized to access a web page that is specifically related to the coordinates. The other way is to include the coordinates in a server-side persistent state, relying on a “session” with the user. The former approach has advantages over the latter, in that it requires significantly less infrastructure on the server side, and provides additional conveniences to users such as the ability to bookmark map pages. However, URLs are subject to significant length constraints, particularly in association with mobile devices. It is advantageous for URLs to be as short as possible, and preferably be human-typeable.
A point on the earth's surface is commonly represented by a pair of floating-point numbers, namely, numerical representations of latitude and longitude. A common representation of such numerical values in computer applications is in decimal degrees. A 1-degree arc of the earth's surface is roughly 110,000 meters long. This means that each latitude and longitude coordinate value must extend to five decimal places in order to yield roughly a 1-meter accuracy of representation. Thus, a typical text representation of latitude/longitude coordinates in the context of a computer application (i.e., encoded within a URL) might look something like:                122.12926,47.64932        
In this representation, longitude and latitude are listed with a separator character (,) between them. The representation requires 19 characters to indicate the longitude/latitude position. Because it is desirable to keep URLs as short as possible, it would be beneficial to represent the same type of position information, to approximately the same accuracy, using a smaller number of characters.